It’s not often you can call a $1.5 million fire a success story, but the explosion and fire at the Woburn Nursing Center in Woburn, Massachusetts, was just that.

On October 31, 1992, the facility housed 101 residents. That afternoon, a plumber charged a natural gas branch line he had been working on, unaware that another plumber who had installed the line earlier had left an opening in a tee fitting unplugged. When the gas pressure failed to stabilize, the man went looking for a leak in the system. Meanwhile, the gas “flowed freely for 15 to 20 minutes,” until 300 to 500 cubic feet (8.5 to 14 cubic meters) of it filled the building, according to NFPA Fire Investigator Michael Isner, who reported on the incident. Nursing home staffers smelled the gas and alerted maintenance personnel, who searched for the source, and began opening windows.

The gas exploded at around 3:45 p.m., blowing part of the three-story building’s roof into a nearby cemetery and starting a fire in the area of the blast. The staff reacted immediately, and began closing resident room doors and evacuating patients from rooms nearest the fire, with the help of neighbors and construction workers. Twenty-one sprinklers operated, confining the blaze mostly to the area of the explosion.

The fire department received an automatic alarm at 4:07 p.m., and responding firefighters soon called in a second and third alarm. Fire Chief Robert Doherty also arrived, and found the dazed plumber walking down the street, according to an article in the Boston Herald. “He was in shock and didn’t know where he was and had second- and third-degree burns,” Doherty said. Doherty ordered a fourth alarm at 4:12 p.m., and the fire was extinguished at 5:15 p.m.

Despite the violence of the explosion, and the ensuing fire, no one died that day — 21 civilians and two firefighters were injured — and NFPA’s Isner says four factors contributed to the successful outcome. The facility had a functioning sprinkler system that operated as designed; the administration had developed programs and procedures for staff emergency response; the staff followed those procedures immediately; and the fire department responded quickly. Everything worked as it should and, as Chief Doherty said later, “everyone worked together.”

“It only took us seven or eight minutes to get everyone out,” he noted. “The EMTs, nursing home staff, police, and firemen were fantastic.”